1. Field of the Invention
This invention relates to optical gain media and, more particularly, to a semiconductor optical gain medium that exhibits low crosstalk.
2. Background of the Related Art
There is a continuing need for optical amplifiers and switches for various optical communication applications, such as optical networking, wavelength-division-multiplexing and other telecommunications applications. Semiconductor optical amplifiers (SOAs) are promising candidates for optical amplifiers and switches due to their relatively simple structure, and the ease with which they can be integrated into optical systems.
However, prior SOAs exhibit crosstalk between different wavelength division multiplexed (WDM) channels due to gain saturation effects and short carrier lifetimes. Such crosstalk limits the performance of prior SOAs in WDM systems.
FIG. 1 shows the effect of drive current I on gain saturation effects in SOAs. More particularly, gain saturation effects in SOAs can be reduced by exponentially increasing the drive current I1 through IN injected into the SOA 50 as a function of position along the waveguide direction (x-axis). Such a scheme would require multiple electrodes 60, and would be very complicated and expensive to implement.